Articles formed by extrusion or compression molding, or by a related process or apparatus, are generally made from a composition material. Before fabrication begins, the composition material is prepared from its constituent chemicals which may reside in separate silos or other storage facilities. Each storage facility is permanently connected by means of a pipe or the like to a receiving point of a transfer area where appropriate interconnections are made to transfer each received constituent to a particular delivery point, as determined by the operation which is to be carried out. Each delivery point is permanently connected by a pipe or the like to a location outside the transfer area where further processing or fabricating steps are performed. For example, a delivery point may be coupled to a mixer, a blender, a verification bin, etc., or it may be coupled directly to an extrusion or injection molding device.
The transfer area in existing installations typically consists of an enclosed room having the aforesaid receiving and delivery points permanently embedded in the walls, or in the ceiling and floor of the room. The number of receiving points may be more or fewer than the number of delivery points. Within the transfer area, each receiving point is permanently coupled to a flexible hose, e.g. a metal hose, or to a hose that is rigid in part but which has a flexible end portion. Each delivery point is permanently coupled to a fixed interconnection station within the transfer area. It will be understood that, although the aforesaid coupling connections are designated and intended to be permanent connections, they can be dismantled or shifted if required.
In order to link certain specified receiving points with designated delivery points, as required by a particular operation, the flexible hoses that are permanently coupled to the specified receiving points are selected for connection to selected fixed stations, the latter corresponding to the designated delivery points. The interconnection between the selected hoses and the selected fixed stations is normally made manually in the transfer area.
Each chosen operation requires a specific set of operating parameters which determine such factors as the feed rate of a particular chemical constituent material, the duration of feed, temperature, etc. These operating parameters are established through a manual interlock system in communication with a computer that supervises the overall process to be carried out. In the arrangement described above, the computer sets the appropriate parameters when it is notified of the chosen operation, i.e. when it is informed of the paths established by the connection of the selected flexible hoses to the selected interconnection station. Notification occurs by way of an electrical signal which is transmitted through a communication channel established at the time each interconnection is made.
In a commonly used arrangement, each fixed station has an electrical receptacle associated therewith to which a male connector portion, attached to the flexible metal hose, is connected whenever the flexible hose is to be coupled to the fixed station. In one example, a 2-part connector which is commercially available as a Cannon plug, includes a male connector portion attached to the flexible hose. The connector portion has pins that engage corresponding holes in the electrical receptacle that is positioned on or near the selected fixed station.
A number of problems arise from such an arrangement, all related to the physical environment of the transfer area. The atmosphere of the transfer area, particularly if enclosed, is usually heavy with the chemicals carried by the flexible metal hoses that are manually connected and interconnected within the room. Unless both parts of the electrical connector are shielded when disconnected, the chemical dust can intrude and foul one or more pin connections. Where such is the case, it may result in the transmission of an incorrect signal to the computer, so that a false set of operating parameters is established.
In addition to fouling, the typical electrical connector frequently cannot withstand the rough handling that is common in the environment described. When a pin is bent or breaks, e.g. during the connection or disconnection of the two connector halves, it either prevents an electrical connection from being established, or it can result in the transmission of an incorrect signal to the computer. Such pin damage can also occur when the relatively heavy end of a flexible metal hose is dropped on the electrical connector, a not infrequent occurrence when a hose is disconnected. Finally, the atmosphere in the transfer area may be explosive, depending on the chemicals being mixed. Where that is the case, the interconnection and disconnection, particularly the latter, of the separate connector halves poses a danger due to the possibility of sparking.